Partial pressure process of making acetylene and other products



Oct. 4, 1932.

PARTIAL PRESSURE PROCESS OF MAKING ACETYLENE AND OTHER PRODUCTS FiledOGt. 2, 1928 4 Sheets-Sheet l Omi mt Oct. 4, 1932. R. G. wULFF 1,380,309

PARTIAL PRESSURE PROCESS 0F MAKING ACTYLENE AND OTHER PRODUCTS Filedoct. 2, 1928 4 sheets-Sheet 2 Oct. 4, 1932.

R. G. wuLFF 1,880,309

Filed 0Ct- 2. 1928 4 Sheets-Sheet 3 Oct. 4, 1932. R. G. wuLl-F 1,880,309

PARTIAL PRESSURE PROCESS OF MAKING ACETYLENE AND OTHER PRODUCTS Filed0M.. 2, 1928 4 Sheets-Sheet 4 ETTQHVEY Patented Oct. 4, 1932 UNITEDSTATES `ROIBI'LB'ZL G. WULFF, OF LOS lANGEELES, CALIFORNIA PARTIALPRESSURE PROCESS OF MAKING ACETYLENE AND OTHER PRODUCTS Application ledOctober 2, 1928. Serial No. 309,749.

This invention relates to the production of acetylene, and a variety ofgases, oils and tars from other hydrocarbons.

It has for its object the cheaper and more efficient production ofacetylene, with its by-products of oils, tars, gases, and othersubstances, from a variety of raw materials among which are natural gas,artificial illuminating gas, casing-head gasoline, gasoline vapor, oilvapor, gas oil vapor, paratlin series hydrocarbons, olene serieshydrocarbons and the cyclic hydrocarbons of the naphthene and benzeneseries. The gases produced from these raw materials and other materialsmechanically equivalent thereto are hereinafter referred to as suitablegaseous raw material.

The invention resides in the selection of raw materials, their treatmentas to temperature, pressure, dilution, time of treatment, exposure to acontact mass, kinds of contact masses, apparatus employed, ow rates, andthe treatment of the reaction products after they are generated, andother details as will hereinafter appear.

Fundamentally, my process is one of heat treating hydrocarbons ormixtures of hydrocarbons while diluted with steam, mercury vapor,nitrogen, methane, carbon monoxide, or hydrogen, or any combination ofthese, for a certain period of time and cooling rap idly thereafter.

My experiments indicate that a suitable gaseous raw material can beproduced from the following substances or combinations thereof, or fromtheir mechanical equivalents:

1. Paralins.

a. Pure-methane.

b. Pure ethane.

c. Casing-head gasoline vapor.

d. Natural gas consisting of CH4 and 15% higher hydrocarbons.

1. ParaIins.-0ontz'nued.

e. Gas oil containing from 30% to 35% naphthenes, 10-12% aromatics,remainder paraiins.

Crude petroleum, kerosene, gasoline or any other liquid fraction.

. Natural gas carburetted with casing-head gasoline or any otherfraction of crude petroleum, including normally gaseous hydrocarbons.

2. Oletines.

a. Ethylene.

b. Higher oletines.

3. Naphthenes.

a. rlhose in gas oil.

Aromatic hydrocarbons.

a. Benzol.

b. rIoluol.

While it has been found that acetylene can be formed from methane,according to my process, it should be stated that yields are low incomparison to those obtained from ethane or higher members. I thereforeprefer, in using natural gas as raw material, to use gas as high inhigher members of the paraiin and olefine series as possible.

In doing so, I prefer to use the apparatus shown in the accompanyingdrawings, Figs.

41 and 2. When operating on a laboratory scale the apparatus of Fig. 1will be used. In the drawings it is shown more or less diagrammaticallyin side elevation. On an industrial scale I prefer to use the apparatusshown in Fig. 2, also shown diagrammatically inside elevation. It is tobe understood that other apparatus may be used to carry out my process.Figs. 3 and 4 are collections o curves which will be later discussed indetail, which graphically indicate the intlu'ence of time, temperature,and other :Eac-

tors in my process. i

Referring again to Fig. 1, numeral 1 indicates an oil supply reservoir,2 a water supply, and 3 3 delivery pipes for each, these supplying abouta ten foot head. 4 and 5 represent oil and water meters, respectively,of the orifice type, 4a and 5 being manometers for gauging the fiow. 6and 7 are needle valves for regulating the fiow of oil and water,respectively. 8 is a water boiling' tube, this being merely a brass orsteel tube wound externally with nichrome resistance Wire. It may beadapted for generating mercury vapor in place of steam. Duets leadingsteam from the tube 8 to the vaporizing and mixing tube 10 are shown at9--9-9-9. The superheated steam generated in the tube 8 meets the streamof metered oil in the steel tube 10 and vaporizes it. If necessary, thetube 10 may also be externally heated to insure total vaporization oftheoil and its efficient admixture to the entering steam. 11 is a packinggland at the far end of the tube 10, joining the tube 10 with the tube12 in gas-tight manner, while 12 is the treating tube itself, which maybe porcelain or sillimanite, but is made preferably of fused silica, ofWall thickness depending upon the tube size. It may be filled withcarborundum or other refractory ygrain or crystals (not shown). Copperand iron must be absent from the hot Zone of the tube, since theydecompose acetylene at high temperatures. 13 is a furnace surroundingthe tube 12, containing carborundum rods 14, these constituting theheating element.

A thermo-couple is placed next the treating tube 12 at 15, the sensitivejunction of which is shown at 15h. It is connected to an indicatingpyrometer 15f. The temperatures given herein, are therefore those of theoutside of the tube 12, as measured at 15b, which is near the hottestportion of said tube. 16 is a condenser of the Liebig type, through thejacket of which cooling water is circulated. Condensed steam from thetube 12 finds an outlet through a U-tube 17. A gas sampling bulb 18 isplaced in the line and it is from the point shown that samples weretaken as a basis for the data to be given later. 19 is a gas meteradapted to measure the output of the installation. While in theforegoing explanation of the apparatus of Fig. l the raw material formaking acetylene was called oil, any hydrocarbon capable of producing asuitable raw material is operative, and if said hydrocarbon is gaseous,the equipment of Fig. l can be modified to use said gaseous rawmaterial.

The large scale apparatus represented in Fig. 2 comprises an oil or gassupplying line 47 in which there is a valve 47 a and a meter 49. Theline is joined with a vaporizing and mixing pipe 43, into which seyera-lcross pipes 45 deliver steam from the header 44. The lower part 46 ofthe vaporizing pipe 43 leads to an oil or gas-fired furnace 20, housinga carborundum (or equivalent) treating tube 21, about 12 feet long andabout 8 inches inside diameter, which is filled with broken orcrystalline carborundum, quartz or sillimanite or other suitablerefractory, (not shown) and touching which is a thermo-couple 54, whichis connected to an indicating pyrometer 54. s

The arrangement in the furnace may be of about six treating tubes ofabout 8 inches inside diameter, these being filled with loose refractorycrystals or broken pieces, or any of the conventional forms of towerpacking.

These treating tubes may be joined in parallel or in series, or in anydesired seriesparallel arrangement. The filler serves the purpose ofstirring the gas or vapor mixture and is desirable in accomplishingquick heating in large tubes. The tube is supported by piers 22 atvarious points. A gland or stuffing box 50 connects the tubes 46 and 21in a gas-ti ht manner.

Any ind of refractory tube material or filling material may be used. Acarborundum tube with a sillimanite filling can be used, or vice versa.The only conditions to be met are that the materials be sufficientlyrefractory and that they Will not fuse with each other, or bedetrimental to the formation of acetylene or other products desired.

On the far end of the refractory tube 21, there is an exit head 24,bearing a removable cap 24a, through Which the head and tube may becleaned of carbon and tar when necessary. The exit head 24 connects, asto its other end, with a combined condenser and boiler 26 adapted forvaporizing and condensing either water or mercury. The latter consistsof a shell and two headers 25 and 28, connected by a large number oftubes as at 39, which in this case should not be made of copper. Infact, no portion of the equipment coming in Contact with acetyleneshould be of copper. Thin steel tubes are preferred, and these may beoff stainless alloy or otherwise rustroo p The headers and tubes are soarranged that gases coming to the condenser are handled within theheaders and tubes, heat transfer occurring through the Walls of thetubes. The condenser is in a canted position so that a space about the.place of entry of the pipe 40 is clear of water when the Water level inthe condenser is near the top. A downeoming pipe 29 serves to drainWater from the condenser to an auxiliary cooler 31, of similarconstruction, but in horizontal position.

Warm Water is furnished the auxiliary cooler by gravity and it is.returned to the condenser after being cooled, by means of a pipe 35 andpump 36. A filter 52 is connected into the pipe line 35 to remove anysolid impurities which may have been introduced into the water. A devicefor separating emulsified oil or otherwise conditioning or purifying thewater may also be introduced into the line atrthis point.

Encircling the upper part of the condenser and boiler 26 is a heater,preferably gas-fired. Its function is to generate steam or mercury vaporin the upper part of the boiler and condenser. The pipe and blower 41are provided to transfer the steam formed inthe transferred therethrough the pipe by a blower 56 through a manifold 57. A pipe 58 alsocarries a gas to the steam generator 26. The apparatus of Fig. 2 is alsooperative in using any hydrocarbon raw material for producing acetyleneas listed above, and can be adapted to that end, whether saidhydrocarbon is normally liquid or gaseous. So can said. apparatus,either of Fig. 1 or Fig. 2 be adapted to the use of mercury or water asdiluent, or to the use of substantially non-condensible diluents listedabove as being op'- erative.

The method of operation of the apparatus of Fig. 1 is as follows:

The valves 6 and 7 are opened until the meters 4 and 5 give properreadings of the respective rates of flow. Oil and water then flow fromtheir respective receptacles 1 and 2. The current for heating thefurnace 13 has meanwhile been switched on. The tube 8 is likewisemeanwhile heated. Metered water entering the tube 8 is thereforeimmediately converted into steam which enters the cross tubes 9, meetingthe oil stream in the tube 10, where said oil is vaporized. The tube 10may be heated externally in any Conventional manner if necessary toaccomplish full vaporization of the oil and its eicient mixing with thesteam.

The mixture of oil vapor and steam then passes into the cracking tube12, which may be made of kieselguhr and clay composition, carborundum,fused silica, sillimanite, porcelain or other ceramic and refractorymaterials. Its temperature is not less than 1500o F. and may be as highas 3500o F. The higher temperatures are preferred.

The tube is of such a length and the flow of vapor so regulated that thetime of exposure of the mixed vapors to the heat lof the furnace rangesfrom 2/1000 second to 5 seconds, depending upon the temperature ofoperation, and the amount of cracking surface exposed to the vapors. Theamount of dilution of the oil vapor by steam or other diluent is suchthat the partial vapor pressure of the oil vapor ranges from just belowatmospheric to approximatel -1/20 inch of mercury, absolute pressure. elower pressures are preferred since they induce less carbonization andform acetylene more efficiently.

Thel cracking tube 12 is preferably filled throughout its length, whichapproximates 18 inches, with carborundum gram, the size of which isabout 1/4, the inside diameter of the tube. The tube itself has aninternal diameter of about one inch.

It lies within the capabilities of persons skilled in this art, suchaschemical engineers to adapt either of the plants, shown in Figs. 1 or 2,to operation with mercury vapor, hydrogen, carbon monoxide, methane ornitrogen as a diluent. The use of mercury will involve the addition of amercury boiler made of steel with suitable burners for heating it. Theboiler will be so arranged as to maintain a pressure of (preferably) oneatmosphere pressure of mercury vapor therein. Pres- `sures much inexcess of one atmosphere should not be employed because the accompanyinghigh temperature of the vapor will give rise to a crackin action on theoil before thorough mixing Wit the oil takes place. It is desirable toaccomplish dilution before any cracking takes place.

My method of making acetylene by the heat treatment of hydrocarbonsmixed with a diluent constitutes one phase of my broad inventiondescribed in my copending application, Serial No. 281,406, filed May 29,1928.

This present application is a continuation in part of the applicationjust referred to in respect to the dilution-employing methods andapparatus herein described. The use of a diluent of my present processis one means of attaining an absolute pressure less than atmospheric forthe hydrocarbons when these are under heat treatment. Tn othery words,

mixing them with a diluent places them under a partial vapor pressure.This term is used in the sense that physical chemists employ it and willbe understood by such' persons and in general by all competent chemistsand chemical engineers. llt is to be brought out that steam and mercuryare preferred diluents because they are easily condensible an( ".husyield a gas much more highly concentrated with respect to acetylene,allylene and ethylene gases. This of course makes thesubsequentisolation of these desired gaseous constituents more easy andpractical. So are water and mercury to be preferred over normally soliddiluents conceivably usable, because they are easier to handle.

The following data is a report of the' results obtained in puttingthrough the apparatus of Fig. 1 a gas oil purchased from the GeneralPetroleum Corporation of California. Tt is known as their gas oil No. 1,,and contains from 30% to 35% of naphthenes, 10-12% aro- .isol

matics and the remainder paraflin series h drocarbons. In some of thetests, as will noted on the tables below, the tube diameter was changedfor examination of the effect of tube size on formation of acetylene. Inthe case of all data given herein, however, the several cracking tubesWere heated in the same furnace, and therefore were heated for the samelength, so that a comparison be- I tween tubes was possible based oninternal cross-section which governed the time of cracking at any onerate of oil and steam flow. Explanation of captions, applying to Tables1, 2, 3.

a. Test number. Lb. per hour of stealn. c. Lb. per hour of oil. d.Millimeter-s of mercury pressure (partial) of oil before cracking. e.Millimeters mercury partial pressure of the fixed gas beforecondensation of the steam, but after completion of cracking.` f. Cu. ft.per hour of fixed gas formed,

room temperature and one atmosphere absolute pressure. TemperatureFahrenheit (approximately the maximum temperature on the outside wall ofthe tube at it hottest point).

L. Time constant, derived by dividing the square of the internal tubediameter by the cu. ft. per hour of steam. Here the diameter isexpressed in inches and the steam volume as reduced to one atmos phereabsolute pressure and room temperature. For example, thus one pound ofsteam would represent 21.3 cu. ft. assuming that the steam would remainin the vapor phase at room temperature and one atmosphere absolute. Thisterm is used merely because of the facility of computation and for allpurposes here is proportional to the actual volume occupied at any onetemperature. It must be realized that as the oil and steam mixturestarts through the tube it is increasing steadily in temperature andtherefore expanding partly from this cause alone before any crackingtakes place. The steam and oil volume is therefore constant at no timeand the time of heating therefore very difficult to arrive at.

2'. Percent by volume of acetylene in the fixed gas.

j. Efiiciency of conversion of oil into acetylene. Expressed in percentby weight.

TABLE No. 1,-34'* inside diameter stllimanite cracking tube, 0.08" tubewall. Not filled with refractory a b c d e f 0 h i j In the first fourtests there was varied nothing but the temperature so as to see theeffect on the acetylene percentage and the efficiency of formation.

The .fifth testshows a little higher oil and steam rates of flow overthe first four. It should be stated that throughout this description, inalll tests mentioned and for which data are given herein, the proportionof oil to Water flow was held constant. The constancy of the proportionof oil to Water may be seen from the listed partial pressure of the oilvapor in the mixture, item d of the tables.

Tests 119-122 inclusive show a still larger flow of oil and steam overthe previous ones. Thus, in these three groups of tests indicated thereis a change in the time of heating due to the hourly passage ofdifferent amounts of steam and oil through the same tube.

The study of the foregoing table as Well as that of others to followwill be easier from curves to be given herein. In this manner it will bemuch easier to see the different effects and to appreciate the reasonfor the different experiments.

Full discussion of the tests will be given mainly with reference to thecurves of Figs. 3 and 4 after all the data has been given. Test numberswill be found to identify the points so plotted so as to facilitatereference to the curves and tables. y

TABLE No. 2 04" inside diameter fused silica tube.

Not filled with refractory. 1,45" tube wall. Apparatus of Fig. 1

a b c d e f a h x j 123 492 0181 3. 53 18. 25 258 2003 15. 25 11. 88 11.5 124 547 0184 3. 23 17. 67 278 21(1) 13; 72 13. 66 13. 9 125 507 01823. 45 24. 4 359 2198 14. 77 14. 80 19. 8 126 520 0180 3. 32 4 435 23(1)14. 38 13. 30 21. 7 127 829 0230 2. 67 13. 63 323 21(1) 9. 04 12. 50 11.9 128 644 0230 3. 43 16. 07 297 21(1) 11. 62 11. 78 10. 3 129 630 02353. 58 21. 9 4m 22M 11. 90 13. 98 16.1 130 607 0231 I 3. 64 25. 8 45523(1) 12. 34 13. 87 18. 5

Tests 123 to 126 inclusive were intended t0 show the variation ofacetylene percentage with temperature as well as the variation in theefiiciency of conversion with temperature, everything else heldconstant.l Test 127 was intended to be a larger flow of oil and steam inproportion to those preceding. Actually the Water flow was higher thanWanted and this was corrected in the tests 128-130 followpreceding,meaning a shorter time of heating.

arriving at the figure called the ing. These last three tests areintended toA have constant conditions eacept f or temperature, again tosee the variation 1n acetylene percent and efficiency of formatlon.

Theabove results show that 1t 1s posslble to obtain, by the use of asmall bore, unfilled refractor tube, percentages of acetylene that thenearly as high as those obtained 1n filled tubes of larger bore. This isprobably because intimate contact is obtained between the gas and thetube wall on account of the small bore. TABLE No. 3.%" inside diameterfused silica tube filled with 8 mesh carborundum gra/in (crystals) 1,/8tube wall. Apparatus of Fig. 1

a b c e f h Tests 131-136 have constant conditions except for thetemperature which was varied to see the eiect on the acetylenepercentage and conversion eiiieiency. Tests 137-142 are the same atahigher oil and steam flow than the Tests 143-145 are the same thingagain at a still higher oil and steam rate of flow. Tests 146-148 werecarried out at a constant temperature butvarying the rate of oil andsteam How, the reason for which will be apparent from the discussionbelow.

An example is here given of the method of time constant, item 7L of thetables.

Lb./hr or steam X 21.35 gives cu. ft./h r of steam, this being thevolume of the steam 1f 1t were cooled to room temperature and still heldat one atmosphere without condensatlon. Actually this is impossible butit is stlll a valid constant for the time of crackingcomparison.

Thus as in test No. 114, We have .403 X 21.35 =8.58 cu. ft/hr of steam.Tube diameter (ll)2=.0625 then (0625/858) 1000 6.

In the case of the 7/8 tube which was filled with carborundum crystals,it wasassumed that the actual free volume of the tube was half of whatit would be empty. This is pretty closely true, for instance, when suchcrystals are used to till a container of about a half pint capacity.

So far it is apparent that the best found given temperature show thatthe higher the temperature the greater the percentage of Y acetylene inthe permanently formed gas and also the higher the temperature thegreater the eciency of acetylene production. or conversion of the oil.

Referring now.to curves 2, 3, and 4, Fig. 4, which represent the testson the 7/8 tube, it is clear that the acetylene percentage passesthrough a maximum as the temperature is increased. This maximum occursat a higher temperature the shorter the time of heating or the smallerthe time constant. This can mean partly that it takes a highertemperature difference between the outside wall of the tube and theinside to ass the heat required on account of the higher rate of gastreatment, and also that ythe higher temperature thus will be necessaryyto increase the rate of cracking and acetylene formation. y

It is also obvious from curves 11, 12 and 13 of Fig.`3 that after themaximum of acetylene at any one temperature has been formed, anycontinued heating is very detrimental to the percentage of acetylene. f

Another fact is that the higher the temperature, the higher the maximum,percentage of acetylene, as is seen .from the curves.

Curves 10-14 of Fig. 3 were derived from the curves 1, 2, 3 and 4 ofFig. 4, together with other data in the tables. It is obvious that thehigher the temperature, the more positive the increase in acetylenepercentage with the decrease in time of heating between the time limits10 to 26. It must also be true that the higher the temperature thesmaller the time at which the maximum percent of acetylene appears. Itis proved on these curves definitely that at 2200o F. there is a fairlysharp peak at a time of 7, and that at 20000 F. there is a maximum,somewhere on the time scale at a value much larger than 7. It is alsoseen that the higher the temperature of operation the more narrow is thepractical range of time of heating. Compare Curves 11 and 13. Thereforethe higher the temperature of operation the more accurately the time ofheating has to be controlled and the more accurately the temperature aswell must be controlled.

For operation of the apparatus of Fig. 1, I

tures around 1400o F. may be increased to as much as five seconds.

The tables of data show that the eiciency ,with which oil is convertedto acetylene increases with the acetylene percentage, but that there isa tendency for the maximum efficiency to occur at a temperature higherthan that at which the maximumacetylene ercentage occurs, given any onetime of heating. However, test 147 at once shows the highest acetylenepercentage obtained by this 10 process, and also the highest eiciency ofacetylene formation from oil.

Another advantage of this process is that the carbon that is alwaysformed from crack- 3 64 ing oil, usually in the hottest part of thetube,

will in this process not accumulate, or can be removed. Water vapor Willcertainly be removing carbon at an appreciable rate as it forms. If itforms in a commercial furnace more rapidly than the water vapor removesit, it will only be necessary in practice to turn the oil oil' for awhile, suspending acetylene formation to clean the tube out.

The heat balance will not be very seriously interfered with due to thefact that there is so much steam going through in operation compared tothe amount of oil. Certainly,

after such a cleaning there would be much less time lost than if it werenecessary to cool down and probably less time lost even 3 than ifinstead of cooling down, production was shut ofi' and air run through.This latter would probably be the easiest means of removing accumulatedcarbon in the case of the mercury process, although in said mercuryprocess steam may be used intermittently for cleaning, or evencontinuously during operation of the process.

The carbon removing action in the case -of Water is of course that ofthe water gas reaction in which the carbon by reacting with the steam isconverted to carbon monoxide and removed as a gas. In the case of usingair', it would be one of carbon monoxide and carbon dioxide formation aswell, with their removal as gases.

It will probably be advisable to circulate the water used as a diluentduring operation and so save acetylene dissolved therein uponcondensation of the water, since the solubility of acetylene in water isappreciable. Besides that, there will probably be by-products ofyaluecontained in the water that would be worth extraction. e

Complete data on the composition of the non-acetylene reaction productsis not yet available. CO is present at a fairly constant percentageapproximating 15, when steam is used as diluent with oil.

Herewith is given a. table of illustrative gas analyses whereconstituents are reported in volume percent. Alkylenes are hydrocarbonsof the ethylene series, exclusive of S ethylene, which is separatelyreported. Test 'rest 11g).I CH, CH C0 3,38 '29 16.50 .e5 15.60 I48.150

Alkylenes 0.00

Test 115. 2. 26 31 Test 126. 31 2. 40 14. 02 10.00

Test 126 was examined for allylene or methyl acetylene CH3.C:CH andshowed 2.20% by volume. n :.[t may be seen from these gas analyses that1t 1s not necessary to the success of the process thatthe diluent whichin these cases was steam, be totally inert and unreactive with the oilvapor or its intermediately formed products in the treating tube. Herethere was a very appreciable formation of carbon monoxide which did'notprevent the formation of acetylene or other of the constituents listed.

The operation of the apparatus shown in Fig. '2 is similar in generalprinciple to that shown in Fig.` 1. The vaporization of the oil takesplace in the tube 43 by means of steam furnished from the header 44 andthe eiiicient mixing of steam and oil is accomplished therein. Thecracking tube 21 is governed as to its length and temperature by thesarge considerations given for the tube o Fig. 1. The contact mass(carborundum, quartz, sillimanite or equivalent) may, however, be of agrain size much less than 1/4 the inside diameter of the tube.

If more than one tube is used, means may be provided for cutting out anyone of the tubes for cleaning (removal of carbon and tar) while theother tubes are left undisturb-| edly operating. To clean out any onetube, steam may be blown through it while the tube is still hot, therebyoxidizing the carbonaceous matter by a reaction similar to the water gasreaction. To accomplish a continuous cleaning, mixtures of diluents maybe used in the main process, speciiically a mixture of mercury vapor andsteam.

The treated gases pass into the tubes of the condenser and boiler 26,meeting first a steam zone and assisting the heater 53 in the generationof steam. They then pass down into the water zone Where they are quicklycooled by the stream of Water entering from the pipe 35.

Here, water condenses and the fixed gases then pass into the lowerheader 28 and find an exit through the pipe 38, while the conffl@ densedwater is also recovered at 29 and may be returned to the system.'I`heoperation of the superhcater and auxiliary cooler will beself-evident.

The condenser and boiler 26 is therefore also a heat interchanger servinto recover the heat content of the steam an other gases issuing from thecracking tube 21 in admixture. Said heat is thus-entering the watercoming from the pipe 35, which surrounds the tubes 27 of the condenser26. The furnace 53 serves the purpose of supplying any deciency of heatrequired for the evaporation oi the required steam ofthe process. rllhesuperheater 42 furnishes any additional heat required to insure thetotal evaporation of the oil in the pipe 43. The auxiliary cooler 3lreduces the temperature of the incoming weter in the pipe 29 sucientlyto render the condenser 26 operative.

The meter 48' of Fig. 2 can be adapted to electrically operate thevalve'l to insure a constant rate of steam or mercury vapor new.Similarly., the meter 49 can be made to control the valve fl'l'. 'lhetemperature of the furnece should be automatically held at the desiredvalue, and any means known to the art mcy be used to accomplish thisresult. In using murcury the iilter or separator 52 shown in Fig. 2should be placed in the line 29 instead of Where it is shown. Whenmercurv condenses in condenser tubes 27, each little droplet will becovered under some of the operating conditions with .a nlm of tar orheavy oil. Separation ot this tar or oil should be ed'ected before saidmercury enters the cooler 31 in order that more efficient heat transfermay taire place in the cooler. lt the mercury descending pipe 29 isallowed to stand in e lil-tube of steel at the height ol ten lect ormore, the oil coating the drops oi' mercury will be squeezed out due tothe weight ol the mercury near the bottom of the itl-tube; @leen mercurycan then be drawn :trom the i'ar arm of the l-tube While the oil willaccumulate above the mercury in the near "the use ci hydrogen can becarried ont, either by adapting a benlr of cylinders of the compressedges to supply the diluent through reducing valves or the hydrogen may besupplied from a gas holder obtaining its supply' under comperntively lowpressnre'trorn stripped water gas, a silicolllprocess plant or from thestripped ges of this process or from eny other oit the' usual commercialmethods el generating hydrogen.

dn apparatus has been invented lor this reaction therefore, in whichthere is marked conservation of heet, fuel, Water and raw materiels..l-leat is recovered by the condensation oit the steam, the water islikewise so recovered end the gas stripped in the stripping plant isstored in the gas holder until it is passed back to the furnace aboutthe crackingtube, and there used as fuel. y

he gases which may be dissolved in water recovered from the pipe 29 canbe saved bythe return of this Water to the steam ator.

In the foregoing matter are illustrated the effects and yields obtainedwhen steam was used as a diluent. 'lhe following tests give the sameinformation for tests generally similar to the steam diluent testsexcept that mcrcury vapor is the diluent. llt is to be noted that insome cases higheryields are obtainable by the use of mercury than arerealized by the use of steam.

The following report of tests give the data obtained by the use ofmercury as a diluent when treating a gas oil purchased from the GeneralPetroleum Corporation of California. lt is known as their gas oil No. land contains from 30% to 35% by weight of naphthenes,10% to 12% ofaromatics, and the generremainder paran series hydrocarbons. The

apparatus ol Fig. 1 was used, employing a M1 i. d. lys" o. d.sillimanite cracking tube.

Explanation of captions a. lest number.

. Lb. per hour of mercury used.

c. Lb. per hour of oil used.

al. Millimeters of mercury partial pres- -sure of the oil vapor bel-orecracking.

e. Millimeters partial pressure ol the xed gas after completion ofcracking but before condensation ofthe mercury.

f. Cu. it. per hour of xed gas formed,

room temperature undone atmosphere eliselute pressure.

g. Temperature Fahrenheit (approximately the maximum temperature on theoutside wall ot the tube at its hottest point).

it. 'llime constant, derived by dividing the square ol the internal tubediameter expressed in inches by the cubic feet per hour of mercuryvapor7 .and then multiplying by 1000. This proximately dependent aloneon the rate at A TABLE No.

a b c d e f g h j In test 104 the total time of treating, that is, thetotal time that the oil and mercury mixture was above room temperaturewas about 0.080 second. The time constant is 8.86 which thus roughlyshows that the time range Within which tests were made in this table isfrom 0.035 to .69 seconds with corresponding time constants 3.942 and 76.1. It is preferred to operate this process above 2200o F. and thepartial pressures of the oil vapor between 1 and 12 millimeters, whenusing gas oil. It is preferred to have the total pressure Within thetreating tube at approximately one atmosphere.

In using the mercury process the tube 21 of Fig. 2 may be cleaned ofcarbon, preferably by rst shutting ofi' the mercury bearing gas andrunning in steam at the lower part of the pipe 46. The ensuing reactionwhich is, in general, an 'oxidizing one between the, steam and thecarbon is an effectual remover of the latter.

I believe that it is new information that mercury vapor is indifferentand does not tend materially to destroy acetylene that is formed, eitherby catalysis or special chemical reaction. It has the additionaladvantage of easy condensability, and another one of its being a liquidat ordinary temperatures so that it will not solidify and so requiremore complicated equipment industrially to keep it in a liquidcondition. Another of its advantages is the large heat transfer that itgives to cooling or heating or heat-exchanging surfaces so as to permitsmaller and so less expensive construction to give a desired capacity ofacetylene production. Another advantage in its use as disclosed is thatit does no t interact with the materials with which it is mixed in sucha way as to deteriorate or to become irrecoverably a part of thepermanently formed gas and so occasion losses of mercury in operation,which would be expensive. Still another of its advantages is that it isone among the conceivably usable metals as a diluent that does not coatand corrode Steel parts lwhich would normally constitute the equipmentof an industrial plant. The inner wall of the steel boiler that I haveused is totally unaffected after considerable use. This last is not anew fact but nevertheless constitutes an advantage.

The following table gives a report of the results obtained when benzolvapor diluted with mercury vapor is treatedl by my process. Here againthe apparatus of Fig. l was used, with a ML i. d., 1%, o. d. sillimanitecracking tube.

Explanation of captions a. Test number.

b. Lb. per hour of mercury used.

c. Lb. per hour of benzol used.

d. Millimeters mercury partial pressure of the benzol before cracking.

e. Millimeters partial pressure of the fixed gas after completion ofcrackng, but before condensation of the mercury.

f. Cu. ft. per hour of fixed gas formed, room temperature and oneatmosphere absolute pressure. y g. Temperature Fahrenheit (approximatelythe maximum temperature on the outside Wall of the tube at its hottestpoint) L. Time constant, derived by dividing the square of the internaltube diameter expressed in inches by the cubic feet per hour of mercuryvapor, and then multiplying by 1000. This volume of mercury vapor isthat computed to room temperature and one atmosphere absolute pressure,although the mercury would not actually exist as a vapor under thoseconditions. Any other arbitrary ratio oftube size to rate of mercury Howwould have done as well, such as the crosssectional area of the tubedivided by the vpounds of mercury per hour. In view of the conditionthat the mercury vapor is present in a. large proportion to the oilvapor in all these tests, the time of treating or cracking isapproximately dependent alone on the rate at which the mercury is passedthrough, and the cross-section of the tube.

Percent by volume of acetylene in the fixed gas.

j. Efliciencv of conversion of benzol int-o acetylene, expressed inpercent by weight.

6 der this condition either forms other liquid or solid products, orcomes through unchanged, and does not form gas.

In comparing the action of benzol in making acetylene to that of oil orparaffin series 10 hydrocarbons in general, I have found that benzol hasa great tendency to form either carbon or other liquid bodies. At hightemperatures the carbon formation predominates, while it is also favoredby the increase in the benzol vapor pressure. At somewhat lowertemperatures the liquid formation is favored, with resulting smallformation of gas. The

' change from one to the other is not so sharp with the paraffin seriesbodies, nor is the eHect of pressure so decided in the formation ofcarbon. Vith the paraffin bodies, liquid condensates and carbon canapparentlyv form together in varying proportions according to thetemperature. With benzol the tendency is to form either one or theother, a comparatively small change in conditions of operation beingcapable of bringing it about.

Data test N o. 103 computed from TabZeNo. 6, anal with analysis of gasformed Mercury vapor fiom-6.41 cu. ft. per hour figured at roomtemperature and one atmosphere.

Gas composition Allyl- Ole- Acety- Parafene C o 0 N Ines Iene H2 C o1111s Percent of oil converted into'acetylene, by weight, 27.5;theoretically possible conver- SlOn, 91.5. I l

` Gas composition oo. 0. N, 213g l legl'Eggl' H. cH. co

In the case of this test there was formed some oil condensed at the.outlet end of the furnacev where the condensed mercury was collected,which might have been unchan ed original oil but more probably was amodi ed oil. It had a yellow color but was not further examined. Thisoil in practical opera.- tion might be mixed with the enterin raw oilfor a second cracking or it might a o be used for fuel. f

Test 102 is incomplete due to the fact that the sillimanite tube whichwas being used as a treating tube plugged up with carbon showing heavyformation of the latter. In test 103 the time of treating nis roughly0.069 second.

A The range of time used is from 0.068 to 0.12

second. While the test just given shows the manufacture of acetylenecontaining gas from benzol vapor, it is to be understood that mercuryvapor may be used not only in connection with benzol but with any of theraw materials listed; likewise steam, hydrogen and nitrogen areacceptable diluents not only with aliphatic hydrocarbons but also thearomatics.

In tests using the combination: casing-head gasoline and mercury, verygood results were obtained. A sample of very light casing-head gas whichshowed pressure in a closed container at room temperature and'which wasrich in ethane and propane was used. It was utilized in gaseous form,made so by spontaneous evaporation and was supplied througha reducingvalve. The apparatus and method was otherwise identical withl that usedin the experiments in which gas oil and mercury were used. Thecomposition of the gaseous product obtained' after treatment was:

Dal-'a est N o. 16M computed from. Table No. 5, 'with analysis of gasformed 'Mercury vapor flow, 7.06cu. ft. per hour figured at-roomtemperature and one atmosy phere.

abcdefghij The comparatively large percentages of eth lene formed durlngthis test and others indicate that this gas might be an intermediateproduct in acetylene formation. Accordingly a guaranteed sample ofethylene was obtained from the Certified Laboratory Products Co. ofGlendale, California, and

lit was heat treated While diluted with mercu vapor, in the sane manneras in the tests wit gas oil, benzol and casing-head gasoline. A seousproduct was obtained showin the folIdwing approximate analysis, as o mytest No. 105:

aar m @o l.7o o o .53 39.9 1.33 30.5 .77 .9s

Since it is a comparatively easy and well known process to make ethylenefrom petroleum oils, it follows that I can also manufacture acetylenefrom oil by a two stage instead of a one stage process. In doing so,

25, I may make ethylene from any liquid petro- I can then crack theethylene while it is mixed leum fraction by any means known to the art.

with mercury vapor, nitrogen or hydrogen and whether or not it isdiluted with the mis` .cellaneous b -product gases of initialmanufacture of et ylene from petroleum.

To obtain a mixture of ethylene and hydrogen, I may use the unseparatedgaseous product of the manufacture of ethylene according f to theprocess of Eldred & Mersereau, United .States Patent No. 1,234,886, July31l 1917.

Such a gas contains about 40% ethylene, methane, hydrogen, and othergases.

`N ot only ethylene seems to be particularly 40. efficacious inproducing acetylene in my process, but also the corresponding paraffin,ethane. Indeed, any chain hydrocarbon has the effect of giving highyields of acetylene in direct proportion to its amount present.

I have even found, for instance, that a natural gas containing 85% ofmethane and total pressure of approximately one atmosphere absolute.Thus, the higher hydrocarbon content may here be regarded as dilutedwith methane which though not under all conditions inert, isnevertheless relatively so. In one case where I had cracked natural gasat atmospheric pressure, I found that the quantity of methane aftertreatment was subis regar ed as important, since natural gas ofsubstantial higher hydrocarbon content and of large methane content, isavailable in many places and is already in a conditionof dilutionsuitable to formation of acetylene by treatment at a total pressure ofapproximately one atmosphere. l

A general summing-up of the chemical principles goerning my process willinclude the following conclusions (among others) 1. The yield ofacetylene is due largely to the conversion of hydrocarbons above methanein the case of aliphatic hydrocarbons. Numerous hydrocarbons ofdifferent series may be employed.

2. Acetylene formation does not occur appreciably below 1500 F. andabove this temperature the acetyleneyield is higher, the higher thetemperature employed in crackin 3. The yield of qacetylene is seriouslyd1- minished if the cracking treatment lasts more than live seconds. Itshould last' more than 0.002 seconds. Quick cooling of the gaseousproduct is essential. The actual most eliicient length of time to cracka hydrocarbon raw material is shorter the higher the temperature. v

4. The diluents employed should be so used as to reduce the partialpressure of the hydrocarbon gas under treatment to 14 millimeters,though higher pressures can be used. The diluent need not necessarily beinert. Partial pressures much below 14 millimeters are well suited tobenzol.

5. Dilution is one way of reducing the pressure on the gasundertreatment. Although the diluted gas mixture may be under a pressurehigher than atmospheric, the partial pressure on the hydrocarbon gas maystill be much less than one atmosphere.

6. Cracking, with consequent formation of acetylene is favored by thepresence of hot refractory contact masses. Their action is notdefinitely catalytic, but seems to be a function of the amount ofsurface presented. If theborelof the reaction tube be sufficiently geolong and narrow (for a given temperature) and the speed of the gasiowing therethrough be sutliciently high, no interior contact mass isnecessary.

7. Paraiiin hydrocarbons all form more or less oil and tar underfavorable conditions for making acetylene. The smaller the parailinmolecule, except for methane, the less oil and tar, and the moreefficient conversion into acetylene. For olefines the same relationshold. Ethylene `makes acetylene very eiiciently, and extremely littleoil or tar.

8. Ethylene is probably an intermediate product in the formation ofacetylene by this process. -Y

9. Allylen'e', and oleines other than ethylene, and ethane can be formedby reducing -the temperature or decreasing the time of acetone, oracetaldehyde or pyridine. Such a. step is to be regarded as a part of myprocess andl may use here the process of my application Serial No.301,402, led August 22,

By operating at the lower temperatures (near 1500O F) the process may bemade to yield acetylene and an increased amount of tar and oil and`ethylene. Such operation may possibly at times be more profitable thanthe production of a gas high in acetylene. The low temperature processis therefore to be regarded as being distinctly Within the scope of myinvention. Thel tars and oils, which are usually produced as fogs, maybe collected by any suitable scrubbing or Washing means, or by anelectrical precipitator.

Indeed, a two-step process of making acetylene is entirely feasible andpractical, the two steps being as follows:

1) Treat any suitable. hydrocarbon, for instance, gas oil. by my processat a temperature approximating; 1500o F. to make a product containing alarge amount of ethylene and unsaturated gases and oils.

(2) Retreat this product at higher temperatures by which a high yield ofacetylene will be obtained due to the suitability of ethylene as astarting material.

The following table gives a synopsis of the results obtained by treatingthe No. l gas oil, before mentioned, by the first step of this processin order to produce a large yield of ethylene:

a. Lbs. mercury used per hour.

I). Lbs. oil used per hour.

c. Cu. ft. gas formed per hour, calculated to one atmosphere absolutepressure and room temperature.

d. Millimeters of mercury partial pressure of oil before cracking.

e. Millimeters of mercury partial pressure of formed gas after coolingand before condensing diluent mercury.

f. Percent by Weight of oil converted into gas.

g. Percent by weight of oil convert-cd into ethylene.

h. Fahrenheit temperature.

` z.. Percent ethylene in the formed gas.

j. Tube size, inside diameter.

'fqta b c d f g n a j e los 3.30 0.1333 1231 4 so 14.55 50.8 19.7 155s34.2 man 109 2.86 0.1333 17,22 4 95 22.9 06.5 26.2 1700 30.9 Z35.7 1101.655.00680 0745 43S 17.47 52.0 18.0 H100 26.0 '/gl 111 1.400.00781 07995 6l 20.7 46.0 19.5 1553 29.3 7/s69.0 112 1.685.(XJ727 0G69 4 61 15.447.8 18.8 1698 32.0 1.; 7.7 113 1.730.00709 0856 3 91 10.1 54.1 21.41842 27.2 3% 7.5

These tests were carried out with the apparatus of Fig. 1. Numberproportional roughly to time of heating.

Sta-tement of gas composition for the above tests: Y

Z. carbon dioxide, C02

m. oxygen, O2

n. mixture of olefines or alkylenes, all except ethylene.

. ethylene, 02H4.

. acetylene, C2H2.

. hydrogen, H2.

. carbon monoxide, CO.

. methane, CIL.

y ethane, (32H6, though there are other paralii s present.

fu.. nitrogen, N2.

'Ilf l m n o p q r s t u y for instance, reacts with the suitablegaseous raw materials or their decomposition products to form a certainamount of carbon monoxide, but this or any similar react-ion does notapprcciably hinder the process. I have used the Words gas and gaseousbroadly, that is, to include not only true gases but also vapors.

I claim as my invention:

1. A process of producing a gaseous'mixture containing a recoverablepercentage of acetylene which comprises: heating a gaseous mixturecontaining gaseousv raw material suitable for the produc-tion ofacetylene, said suitable gaseous raw material being mixed with an inertdiluent, said heating being conducted at a temperature preferablyconsiderably in excess of 1500O F. and for a period of less than fiveseconds and the gaseous mixture being maintained at about atmosphericpressure during said heating; thereafter cooling the heated mixture asrapidly as possible tov a temperature at which acetylene is stable; andseparating the acetylene from the gas'- eous mixture containing it.

A process of producing a gaseous mixture containing a recoverablepercentage of Iacetylene which comprises: heating a gaseous mixturecontaining 'gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being mixed with an inertdilucnt, said heating being conducted at a temperature preferablyconsiderably in excess of 1500o l". and Yfor a period of less than fiveseconds and the gaseous mixture being maintained at about atmosphericpressure during said heating, the proportions ofthe different gases inthe mixture being such that the gas constituting said suitable gaseousraw material is at a partial vapor pressure of less t-han seVenty-vemillimeters of mercury (absolute) during the heating operation andthereafter cooling the heated mixture as rapidly as possible to atemperature at which acetylene is stable.

3. A process of producing a gaseous mixture containing more than tenPercent of acetylene which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being mixed with apreponderant proportion of an inert diluent, said heating beingconducted at a temperature preferably considerably in excess of 1500? F.and for a period of less than live seconds and the gaseous mixture beingmaintained at about atmospheric pressure during said heating; andthereafter cooling the heated mixture as rapidly as possible to atemperature at which acetylene is stable.

4. A process of producing a gaseous mixture containing more than tenpercent of acetylene Which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being mixed with apreponderant proportion of an inert diluent, said heating beingconducted at a temperature preferably considerably in excess of 1500o F.and for a period of less than five seconds and the gaseous mixture beingmaintained at atmospheric pressure during said heating, the proportionsof the different gases in themixture being such that the gasconstituting said suitable gaseous raw material is at a partial vaporpressure of less than seventy-five millimeters of mercury (absolute)-during the heating operation; and

thereafter cooling the heated mixture as rapidly as possible to atemperature at Which acetylene is stable.

5. A process of producing a gaseous mixture containing a recoverablepercentage of acetylene which comprises :heating a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous ran;r material being diluted withsteam, said heating being conducted at a temperature preferablyconsiderably in excess of 1500 F. and for a period of less than fiveseconds and the gaseous mixture being maintained at about atmosphericpressure during said heating; and thereafter cooling the heated mixtureas rapidly as possible to a temperature at which acetylene is stable.

6. A process of producing a gaseous mixture containing a recoverablepercentage of acetylene which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being diluted with steam',said heating being conducted at a temperature preferably considerably inexcess of 1500o F. and for a period of less than five seconds and thegaseous mixture .being maintained at about atmospheric pressure duringsaid heating, the proportions of the different gases in the mixturebeing such that the gas constituting said suitable gaseous raw materialis at a partial vapor pressure of less than seventy-five millimeters ofmercury (absolute) during the heating operation; and thereafter coolingthe heated mixture as rapidly as possible to a temperature at whichacetylene is stable.

7 A process of producing a gaseous mixture containing more than tenpercent of acetylene which comprises: hea-ting a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being diluted With apreponderant proportion of steam, said heating being conducted at atemperature preferably considerably in excess of 1500D F. and for aperiod of less than five seconds and the gaseous mixture beingmaintained at about atmospheric pressure during said heating; andthereafter cooling the heated mixture as rapidly as possible to atemperature at Which acetylene is stable.

8. A process of producing a gaseous mixture containing more than tenpercent of acetylene which comprises: heating a gaseous mixturecontaining gaseous raur material suitable for the production ofacetylene, said suitable gaseous raw material being diluted with apreponderant proportion of steam, said heating being conducted at atemperature preferably considerably in excess of 1500 F. and for aperiod of less than five seconds and the gaseous mixture beingmaintained at about atmospheric pressure during said heating, theproportions of the different gases in the mixture being such that thegas constituting said suitable gaseous raw material is at a partialVapor pressure of less than seventy-five millimeters of mercury(absolute) during the heating operation; and thereafter cooling theheated mixture as rapidly as possible to a temperature at Whichacetylene is stable.

9. A process of producing a gaseous mixture containing a recoverablepercentage of acetylene which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for'` the production ofacetylene, said suitable gaseous raw material being diluted with amercury vapor, said heating being conducted at a temperature preferablyconsiderably in excess of 1500 F. and for a period of less than fiveseconds and the gaseous mixture being maintained at about atmosphericpressure during said heating; and thereafter cooling the heated mixtureas rapidly as possible to a temperature at which acetylene is stable.

10. A process of producing a gaseous mixture containing a recoverablepercentage of acetylene which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for the product-ion ofacetylene, said suitable gaseous raw material being diluted with apreponderant proportion of mercury vapor, said heating being conductedat a bemperature preferably considerably in excess of 1500o F. and for aperiod of less than tive seconds and the gaseous mixture beingmaintained at about atmospheric pressure during said heating, theproportions of the different gases in the mixture being such that thegas constituting said suitable gaseous raw material is at a partialvapor pressure of less than seventy-five millimeters of mercury(absolute) during the heating operation; and thoreafter cooling theheated mixture as rapidly 1s possible to a temperature at whichacetylene is stable.

11. A process of producing a gaseous mixture containing more than tenpercent of l acetylene which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being diluted With apreponderant proportion of mercury vapor, said heating being conductedat a temperature preferably considerably in excess of 1500 F. and for aperiod of less than ve seconds and the gaseous mixture being maintainedat about atmospheric pressure during said heating; and thereaftercooling the heated mixture 'as rapidly as possible to a tem erature atwhich acetylene is stable.

12. process of producing a gaseous mixture containing more than tenpercent of acetylene which comprises: heating a gaseous mixturecontaining gaseous raw material suitable for the production ofacetylene, said suitable gaseous raw material being diluted with apreponderant proportion of mercury vapor, said heating being conductedat a temperature preferably considerably in excess of 1500.o F. and fora period of less than five seconds and vapor pressure of less thanseventy-fivel millimeters of mercury (absolute) during the heatingoperation; and thereafter cooling the heated mixture as rapidly aspossible to a temperature at which acetylene is stable.

In testimony whereof, I have hereunto set my hand at Los Angeles,California, this 25th day of September, 1928.

ROBERT G. WULFF. l

the gaseous mixture being maintained at about atmospheric pressureduring said heating, the proportions of the different gases in themixture being such that the gas constituting said suitable gaseous rawmaterial is at a partial CERTIFICATE oF ooRREcTIoN.

Patent No. 1,880309. I ctoher 4, 1932.

ROBERT G. iiULFF.

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page115,line 21, claim 10, strike out the words "preponderant proportion of";and that the said Letters Patent should'be read with this correctiontherein that the same may conform to the record 0f the case in thePatent Office.

Signed and sealed this 29th day of November, A. D. 1932.

M. J. Moore.

vbien!) Acting Commissioner of Patents.

